The present invention relates to a method of removing air from a liquid channel, for example, of a liquid filling apparatus before the start of a filling operation, the apparatus being adapted to fill a liquid into containers in a specified amount in each container.
Such a method is already known for use in liquid filling apparatus which comprise an apparatus body having a liquid channel connected at one end thereof to a liquid tank and having at the other end thereof an opening serving as an outlet of a filling nozzle, a metering cylinder provided in the liquid channel between opposite ends thereof in communication with the ends, an upper check valve disposed in the liquid channel upstream from the metering cylinder of the liquid channel, a lower check valve provided in the liquid channel downstream from the metering cylinder, and a downflow preventing member provided at the outlet for preventing the liquid to be filled from flowing down under gravity by the surface tension of the liquid. The method comprises the liquid feeding step of closing the lower check valve, opening the upper check valve and feeding the liquid in the tank to the liquid channel to the upstream side of the lower check valve, and the air removing step of opening the lower check valve with the upper check valve held open, causing the liquid to flow from the upstream side of the lower check valve to the downstream side of the lower check valve and discharging air from the downstream side of the lower check valve through the outlet along with the liquid.
This method is adapted to remove air by allowing the liquid to flow out and is unable to discharge air alone from the downstream side of the lower check valve through the outlet, thus inevitably discharging the liquid along with the air. The quantity of the liquid discharged with the air is as much as several liters. This portion of liquid can be handled in no way other than disposal, is uneconomical and results in a very low yield of the liquid to be filled.